Summary of Work: The Baltimore Longitudinal Study of Aging (BLSA), the Intramural NIA's major research program on human aging, has been conducted at the Gerontology Research Center since 1958. The study represents a consortium of scientists who work to characterize normal and pathological aging. The BLSA consists of a series of longitudinal and cross-sectional studies oriented toward characterizing human aging processes. The scientific goals include identifying age differences among individuals and changes in individuals over time; to characterize transitions from normal to pathological aging; to determine the relative contribution of aging, disease processes, cohort effects and secular effects; to expand scientific understanding about predictors and risk factors for specific diseases and for other end points; and where possible to explore mechanisms for normal and/or pathological changes. The Chief, LSS, is the Director, BLSA; LSS staff administer and manage the BLSA operations and the clinical evaluations of the research volunteers. LSS scientists also conduct research with the BLSA. The BLSA Executive Committee, an internally comprised committee of GRC scientists and the Director, BLSA, is responsible for oversight of BLSA operations and research. The total BLSA population as of 9/1/00 includes 1496 participants (757 women; 739 men), 587 inactive (270 women; 317 men), and 855 deceased (130 women; 725 men). At present 20% of all active men and 29% of the active women are African-American. Overall, over 30% of the active participants are members of a minority group. Between 10/1/99 and 9/11/00, 532 participants visited the GRC for the regular 2- to 2-1/2-day visit. This includes 156 new participants. A high priority is systematic follow-up and re-enrollment efforts directed at inactive participants, and attrition prevention strategies targeting currently active participants. Sarah Holmes, Ph.D., Project Director for follow-up, is in charge of this aspect of the program. The transportation program for non-local particiants implemented this year is successful and cost effective. Of the 855 deceased participants, we have death certificates on file for 90%, physician and/or hospital reports for 40%, and autopsy reports for 20%.